The present invention relates to a roll-forming machine of the type which is used to form components, such as purlins, having C-shaped and Z-shaped cross-sections from sheets of planar material.
Roll-forming machines typically include a plurality of roll-forming stations that are used to transform a planar sheet of metal into a component having either a C-shaped or Z-shaped cross-sectional area. The component, such as a C-purlin or Z-purlin, typically has a center portion, a pair of leg portions joined to the center portion by a substantially right angle bend formed by the roll-forming machine, and a flange joined to each leg portion by a respective bend formed by the machine.
Typically, the flanges of a C- or Z-shaped component are made first by a plurality, such as three, roll-forming stations. The first of these stations makes an initial pair of bends at the desired transverse locations on the sheet, and then the successive stations for forming the flanges increase the previously made bends until the flanges are at the proper angle relative to the center portion of the sheet. The legs of the component are then formed by a plurality of roll-forming stations in a similar manner.
Each of the roll-forming stations typically includes a pair of frame members in which a pair of rotatable spindles are journalled, one spindle disposed directly above the other, and a pair of sleeves which cover a portion of the spindles, the sleeves being slidable over the spindles. Each roll-forming station includes at least two pairs of generally cylindrical plates, referred to herein as "forming rolls," two of the forming rolls being fixed to the spindles and the other two forming rolls being fixed to the sleeves. The circumferential ends of the upper and lower forming rolls are vertically spaced apart by a distance corresponding to the thickness of the sheet of material being bent, and the shape or contour of the forming rolls controls the degree to which the sheet is bent. The use of sleeves which are slidable on the spindles and which rotate with the spindles allows the horizontal spacing of the forming rolls on each spindle and sleeve to be varied so that the transverse widths of the center portion and the leg portions of the components being formed can be adjusted.
The sheet of material is forced through the roll-forming machine by friction between the sheet and the rotating forming rolls. The forming rolls of a plurality of the roll-forming stations, e.g. the forming rolls of every other station, are rotatably driven to ensure that there is enough driving power to force the sheet through the machine.
In the case of a C-shaped component, the flanges are made by bending the transverse ends of the sheet in the same direction, for example, downwards, whereas for a Z-shaped component the flanges are made by bending the transverse sheet ends in opposite directions. After the flanges are formed on the transverse ends of the sheet, the legs are formed by a plurality of roll-forming stations by a similar process. To form a component in the above manner, up to ten or more roll-forming stations may be incorporated in the roll-forming machine.
One prior art roll-forming machine incorporates a first set of roll-forming stations adapted to form a Z-shaped component and a second set of roll-forming stations adapted to form a C-shaped component. The two sets of roll-forming stations are driven by a common drive mechanism, connectable to a plurality of roll-forming stations of each set by a pair of coupler mechanisms, so that only one of the sets of roll-forming stations is operable at a time. The forming rolls of both sets of roll-forming stations are horizontally adjustable, as described above, so that the transverse dimensions of the Z- and C-shaped components can be varied.
In the prior art roll-forming machine described above, in order to produce C-shaped components having different transverse dimensions, a pair of forming rolls which were disposed in a number of the roll-forming stations and which were adapted to make flush contact with the flanges of the C-shaped component had to be changed. In particular, where a C-shaped component having a first leg length was to be formed, after the leg portions were substantially formed, the flanges of the component would extend downwards by a distance corresponding to the leg length.
In order to ensure that the forming rolls designed to make flush contact with the flanges made such contact, those forming rolls had to be selected to have a diameter which ensured that the outer cylindrical surfaces of those forming rolls made contact with the flanges of the component. The position of those forming rolls could not be adjusted since they were fixed to a fixed-position spindle and sleeve rotatably journalled in a pair of frame members. Consequently, where C-shaped components having different leg lengths were to be formed, the forming rolls of a number of the roll-forming stations would have to be physically removed and replaced with forming rolls having different diameters.
In the prior art roll-forming machine described above, some of the roll-forming stations used to form Z-shaped components used a pair of angled contact rollers, one of which was disposed to make contact with the Z-shaped component at the inner portion of the bend in the sheet between the center portion and one of the leg portions, and the other of which was disposed to make contact with the Z-shaped component at the inner portion of the bend in the sheet between the center portion and the other leg portion. The position of each of those contact rollers was horizontally adjustable.